TDV was approached by Sinotech Engineering Consultants of Taipei Taiwan in autumn 2000 to check the detail design and drawings as well as to provide specifications for certain special items for the viaduct. TDV completed their assignment in July 2001.

The concrete box girder deck is a triple cell system with an overall width of 28.55 metres, a depth varying between 3.0 metres at mid-span and 5.1 metres over the pier/pylons and a general span of 140 metres. The concrete box girder deck is prestressed both longitudinally and transversely and is additionally supported by a multiple extra-dosed stay cable system. The analysis and design therefore had to consider all the typical problems associated with cable stayed bridges. Additionally the basic design rules for external prestressing have been considered. The girder is internally prestressed as well.

Dou Shan Viaduct, Extradosed Bridge

The variable width pylon that supports the extradosed stay cables to a maximum height of 19 metres above the deck is of reinforced concrete, is centrally located in the deck girder and has a frame shape in the longitudinal direction that is consistent with the pier shape below the deck. There are nine twin extra-dosed cables on either side of each of the 10 pylons each pair of cables picking up a separate deck segment. The Piers varying in height between 36 and 52 metres high, comprise a double legged Vee Frame built-into the deck girder at the top and a single leg stem that is cast into the caisson foundation forming a Y shape in elevation. The bridge is to be built using the cast-in-situ balanced free cantilever method for all of the main spans. The extradosed cables (Stay cables) are stressed during the cantilever construction once the relevant segment has been cast and prestressed. The pylons for the extradosed cables are built during the early stages of the free cantilever. The prestressed concrete box girder deck is also transversely prestressed.

Dou Shan Viaduct, Extradosed Bridge

Contract:

Dou Shan Viaduct, Taiwan

Consultant:

Sinotech Engineering Consultants Ltd., Taiwan

State of Construction:

Completed

TDV Involvement:

Optimising the prestressing cable arrangement and the extradosed stay cable arrangement, recommending a stressing sequence for the extradosed cables.

Making recommendations on the arrangement of the stay cables in the pylon head as well as in the deck girder and providing details of the stay cable force transfer diaphragms.

Making recommendations on the arrangement of the prestressing cables in the box girder for optimum practicality.

Checking the local reinforcement design for the concrete box girder and the pier/pylon and making recommendations on required modifications for the various details.

Checking the drawings and providing technical advice on producing a practical and sound structural solution.